1. Field of the Invention
Castable and curable thermosetting polyurethane polymers; such polymers having improved heat stability.
2. Prior Art
The prior art is replete with castable thermosetting polyurethane polymers of various compositions, and numerous are available in commerce. The systems employed vary from product to product and provide varying properties or characteristics as may be desired in their end use. The castable urethane polymers are used in a wide range of molded products, as is well known in the art. However, when used as a structural component, as an insulating medium in a thermalized (thermal barrier) aluminum extrusion window or door frame, or the like, the available materials have been found to be characterized by various shortcomings which limit their applicability and especially their performance and acceptability in use. In particular, since castable elastomers may in use be subjected to elevated temperatures such as encountered during post finishing, e.g., painting with thermosetting materials including high-temperature thermosetting paints, powder coatings, and anodizings, degradation at such higher temperatures which are encountered in such end use seriously detract from their performance, acceptability, and suitability in actual use. Up to the present, such shortcomings have presented not only a limitation upon the end use of such polyurethane polymers but has also resulted in the development of disadvantageous characteristics when the high-temperature finishing of an end product, commonly referred to as post finishing, has been attempted with conventional or commonly-available castable thermosetting polyurethane polymers. The present development is based upon the selection of a particular polyol and diol resin blend which imparts desirable high-temperature performance characteristics to the castable thermosetting polyurethane polymer of the present invention.
A search conducted according to the USPTO Automated Patent Searching system in Class 264, Subclasses 272.11, 331.12, and 331.16, as well as in Class 428, Subclass 34 and in Class 528, Subclass 73, failed to reveal previous patent literature considered to be even reasonably close to the present development, and a search of the APS full-text data base was also unproductive.